How to pull a realtime list of users using AJAX and PHP from a MySQL database

Not sure exactly how much detail you are looking for here, but here's a high level shot at it;

check_new_users.php

$timestamp = $_GET['timestamp'];
$array_of_new_users = getNewUsersFromDB($timestamp);
echo json_encode(array('new_users' => $array_of_new_users));

check_new_users.js (assuming you have JQuery included)

$(document).ready(function () {

  // function to poll the server and get the new users from your script
  var CheckNewUsers = function () {
    var data = {timestamp : new Date().getTime()};
    $.getJSON("path/to/check_new_users.php", data, function (JSON) {
      var new_users = JSON.new_users,
        rowHTML = '';

      // the exact structure here depends on what the array
      // returned from the function getNewUsersFromDB() looks like
      // lets assume it looks like:
      // array(userid => array(info about the user))
      // E.G.
      // array(1 => array(userid => 1, username => "matt"),
      //       2 => array(userid => 2, username => "joe")...

      // process and display the new users onto your page
      for (userid in new_users){
        u = new_users[userid];
        rowHTML = '<tr><td>' + u.userid + '</td><td>' + u.username '</td></tr>'
        $('#user_table').append(rowHTML);
      }
    }
  };

  // and set the function to run every 5 minutes
  setInterval(CheckNewUsers, 300000);  // 300000 milli = 5 minutes

});

Let me know if you want more detail on any of that I'd be happy to elaborate!

Depending on the CMS you use, this might be easy or hard. Like Nik said, you will need to code a client side site for this that polls the server-side script at set intervals. This shouldn't be too hard, especially using something like jQuery.

On the server side, you need to know whether or not these modifications are stored in a table, or not. Some CMS's might put a timestamp on edits, and new user creation. If this is the case, then you should pass a timestamp to the AJAX page along with any updates. Then on the next poll, include the last timestamp in the request and have the database query for activity where TIME > TIMESTAMP.

You might need to edit the CMS in multiple places to add this functionality, and its hard to say exactly what is needed without knowing more details.

hope this helps, i know i didn't get into the exact details, but this may give you a roadmap.

you can use javascript to poll the server at some regular interval (maybe once every 15 seconds).

it can make an HTTP request to some url dedicated to this purpose, like maybe yoursite.com/poll_for_user_changes. this url, rather than serving HTML web content back, can simply send a JSON object (or some other format of data), which will contain any changes that you would want to know about.

when you hit yoursite.com/poll_for_user_changes, your server is going to have to figure out whether there have been changes to your user table in the database. so it would be helpful if your javascript would keep track of when the browser last received an update from the server, so when it asks for a new update it can send in the get string of the URL (or via post) the last_updated_timestamp of when it last received an update. the server can use this info by building a database query that asks for, for instance, rows in the user table that have a creation timestamp that is > the last_updated_timestamp.

once your javascript receives the data from the server about whether there have been any changes, you will have to decide how to incorporate this data into the website to automatically show the changes without refreshing.